[Q&A+] Landing on Venus, Neutron Stars Going Boom, Shape of the Oort Cloud | Q&A 357
Can neutron stars create an equivalent of Type 1a supernovae? Can you land on Venus without a parachute? How do we know the shape of the Oort cloud? And in Q&A+, what's going on with 3I/ATLAS' weird tail situation?
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Comments (8)
Question: Fraser, I've heard you say a few times, "Gravity travels at the speed of light." But doesn't the Earth orbit the Sun where it actually is and not where it was 8 minutes go? What am I missing?
Question: With the "correct" technology could we see dinosaurs in real time if we were at the right distance (65 million light years) from earth?
A comet loses mass : the gas subliming and being blown by the solar wind. The conservation of momentum tells us then that the speed is affected. But I think the mass lost is negligeable. And there is the question of the direction (momentum is a vector) which would take some (easy) calculations, but not worth my time (sorry).
The discussion of both 3I/ATLAS and the overlapping Oort clouds raises a question for me. Its very high velocity relative to the sun means we know its from outside the solar system. Does that velocity relative to the Sun mean we're fairly confident it doesn't come from any of the solar systems our Oort cloud overlaps with? (Since, presumably, the relative velocity difference the Sun and our nearest neighbors doesn't seem it would be as high as 3I/ATLAS's?) It makes me wonder about the probability distribution, because while in general it seems more likely that the origin system was closer rather than far away (more leeway for flung objects to approach us), there are also many more stars far away than there are very close by, and higher base relative velocity differences, so the interaction of those opposing trends makes me think there must be a theoretical peak in the probability distribution at a certain distance.
And actually, thinking about this the other way, is there anything in principle stopping an interstellar comet or asteroid from approaching us at a low relative velocity to the sun? I can't think of one, and presumably if it happened it would end up simply gravitationally bound to the sun as a new Oort cloud object. If that were to happen, unless we happen to notice something odd about its chemical makeup, there's not any reason we would ever notice that it originated from outside the solar system, right? If I have that all correct, has there been any research into what percentage of the Oort cloud originated in this solar system vs being captured interstellar objects?
Doing my yearly Firefly rewatch (maybe it is q 4-6 mo actually)😉
Is a black hole really a hole, or is it like a big giant ball of mass. Does the things it consumes go into the hole, or does it stick to the "sueface" of the black hole?
Nobody knows by definition. I like to imagine all the matter that ever passed the event horizon spiraling inwards with infinite slowness due to the extreme time dilation.